Question

How can I check the umask of a program which is currently running?

[update: another process, not the current process.]

Answer 1

You can attach gdb to a running process and then call umask in the debugger:

(gdb) attach <your pid> ... (gdb) call umask(0) [Switching to Thread -1217489200 (LWP 11037)] $1 = 18 # this is the umask (gdb) call umask(18) # reset umask $2 = 0 (gdb)  

(note: 18 corresponds to a umask of O22 in this example)

This suggests that there may be a really ugly way to get the umask using ptrace.